Volume Contrast Imaging: A New Approach to Identify Fetal Thoracic Structures

Objective. To assess the potential of volume contrast imaging for evaluation of fetal intrathoracic structures. Methods. Volume contrast imaging is a new ultrasonographic method that increases the contrast between tissues. It consists of a 5- to 10-mm-thick slice-shaped volume image projected on a 2-dimensional screen. The rendering process applied on the slice smoothens the speckle pattern of the image by filling up the gaps with tissue information from the adjacent layers. To evaluate the potential of volume contrast imaging for enhancing the contrast between fetal lungs and surrounding tissues, we compared the ability of volume contrast imaging and conventional ultrasonography to image the fetal thymus in 50 controls. We also applied volume contrast imaging to prenatal imaging of 6 thoracic abnormalities (2 left congenital diaphragmatic hernias, 1 right diaphragmatic hernia, 2 congenital adenomatoid lung malformations, and 1 lung sequestration). Results. In controls, the thymus was identified in all cases by volume contrast imaging and in 42 cases (84%) by conventional 2-dimensional ultrasonography. Clear images of macrocystic and microcystic congenital adenomatoid malformations were obtained by volume contrast imaging, which provided precise contouring of the lesions. In cases with congenital diaphragmatic hernias, volume contrast imaging provided clear images of the limits of the lungs ipsilateral to the hernia. Conclusions. Volume contrast imaging may enhance the contrast between fetal lungs and surrounding organs and can be applied to prenatal imaging of intrathoracic structures in cases with thoracic fetal abnormalities.